“The sharp increase in cases of MDR Acinetobacter baumannii infections in recent years prompted by WHO to list this pathogen as a critical pathogen. The development of new approaches that adjuvant the scarcity of clinically relevant antibiotics for treatment of infections by MDR A. baumannii is an urgent need. Researchers from the University Hospital Virgen del Rocío of Seville, Institute of Biomedicine of Seville, the Hospital Clínic of Barcelone and the Institute for Research in Biomedicine of Barcelone have developed a new cyclic hexapeptide, AOA-2, as a potential inhibitor of outer membrane protein A (OmpA) of Gram negative bacilli.

In this work, they reported that AOA-2 is active in combination with colistin against clinical isolates of colistin-susceptible and colistin-resistant Acinetobacter baumannii. Moreover, mechanistic studies have demonstrated that this synergy between AOA-2 and colistin is mediated by the overexpression of Omp25 in these clinical isolates. Therefore, they showed that AOA-2 in combination with sub-optimal dose of colistin reduces the bacterial loads in tissues in murine peritoneal sepsis model with reduction of mice mortality rate.

The inhibition of OmpA can offer a strategy as adjuvant to address the urgent need for new treatments of infections caused by MDR A. baumannii.”